Objective: The goal of this study is to add to a small, but growing body of research exploring how patients' communication style affects physicians' communication. In particular, we examine how patients' active participation (e.g.. asking questions, providing information) affects physicians' use of patient-centered communication. Methods: The same 25 physicians were observed interacting with high and low participation patients. High participation was defined as the frequency of information seeking/verifying, information provision, assertive utterances, and expressing concerns. On average, physicians interviewed 2.56 high participation patients and 3.44 low participation patients. Transcripts of the interviews were coded for physicians' patient-centered communication. High and low patient participation interviews were then compared using nested ANOVAs. Results: When interacting with high participation patients, physicians engaged in significantly more patient-centered communication overall than when interacting with low participation patients. Analyses on separate components of patient-centeredness indicated that physicians engaged in significantly more exploring of patients' disease and illness, but did not engage in significantly more understanding of the whole person or finding of common ground. Conclusion: Patients who actively participate in medical interviews influence physicians to adopt a more patient-centered style of communication. (c) 2009 Elsevier Ireland Ltd. All rights reserved.